Efficient Photocatalytic Water Splitting Using Al-Doped SrTiO3 Coloaded with Molybdenum Oxide and Rhodium–Chromium Oxide

Al-doped SrTiO3 loaded with a rhodium–chromium mixed oxide (RhCrOx/STO:Al) efficiently promotes photocatalytic overall water splitting with an apparent quantum yield (AQY) of 56% under 365 nm ultraviolet (UV) light. Further increasing this AQY is of vital importance, because this value determines the maximum solar to hydrogen energy conversion efficiency that can be achieved. Herein, we demonstrate that the AQY during overall water splitting by RhCrOx/STO:Al is improved by 20% (to 69% at 365 nm) by coloading of molybdenum oxide (MoOy, 0.03 wt % as Mo) followed by calcination. Reductively photodeposited MoOy modifies the chemical state of the RhCrOx cocatalyst and likely promotes photocatalytic H2 evolution, whereas MoOy loaded onto STO:Al does not catalyze either photocatalytic H2 or O2 evolution. The present study indicates a means of further enhancing the water-splitting activity of highly efficient cocatalyst/photocatalyst composites by loading small amounts of promoters in a facile manner.